Abstract
A new species of Masenia Chatterji, 1933 is described based on material from the intestine of Clarias gariepinus (Burchell) in the Incomati River, Mozambique. The combination of morphological characteristics and analysis of 18S and 28S rDNA sequences delineated the specimens found in the present study as a distinct species. The new form is distinguished from other Masenia spp. in having a large reniform seminal receptacle, a cirrus-sac ending anterior to the ventral sucker, intestinal caeca extending into the hindbody to the level of the posterior testis, and the vitelline fields extending anteriorly to the ventral sucker and posteriorly to the middle of the ovary. Notably, the new form is the only record of African species having a sac-shaped excretory vesicle. Analysis of 28S rDNA sequence data supported its placement in the Cephalogonimidae Looss, 1899. 18S analyses also supported its placement in this family but showed it was not closely related to Masenia bangweulensis (Beverley-Burton, 1962), the sole other African species for which genetic data is currently accessible. The total pairwise differences for 18S and 28S sequences showed the new form differing from other cephalogonimids. Thus, both morphological and genetic characteristics indicate that the present form represents a distinct species, here described as Masenia nkomatiensis n. sp. An updated key to African Masenia spp., now five, is provided.
Highlights
Cephalogonimidae Looss, 1899 is a small family containing small, spinose digeneans parasitic in the gastro-intestinal tract of fishes, amphibians and reptiles (Jones & Bray, 2008)
Adult cephalogonimids have a genital pore at or near the anterior extremity and a long cirrus-sac terminating at different levels in the forebody (Jones & Bray, 2008)
Species delineation within the genus is based on the body shape and size, arrangement of the internal organs, number of the circumoral spines, the shape of the excretory vesicle, the size of the eggs and the extension of vitelline follicles, the caeca and the cirrus-sac (Khalil & Thurston, 1973)
Summary
Cephalogonimidae Looss, 1899 is a small family containing small, spinose digeneans parasitic in the gastro-intestinal tract of fishes, amphibians and reptiles (Jones & Bray, 2008). Adult cephalogonimids have a genital pore at or near the anterior extremity and a long cirrus-sac terminating at different levels in the forebody (Jones & Bray, 2008). It comprises five genera: Cephalogonimus Poirier, 1886; Paracephalogonimus Skrjabin, 1950; Cephalogonimoides Brooks & Buckner, 1976; Emoleptalea Looss, 1900; and Masenia Chatterji, 1933. 22 Masenia spp. are considered valid with a remarkable breadth of fish families infected They are clustered into two groups, those described from Africa and those from Asia (Table 1).
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